Mendoza is said to have been a member of a motorcycle club known as the Mongols, which tangled with another MC, the Iron Order, at the event.

Both the Mongols and the Iron Order were dubbed Outlaw Motorcycle Gangs, or OMGs, in a 2014 study that stressed motorcycle club recruitment of present and past law enforcement officers and individuals associated with the military — and indeed, the Colorado Department of Corrections has confirmed that one of its employees was involved in the Denver incident.

Now, an organization called the National Council of Clubs has issued a press release and accompanying photos via the Motorcycle Profiling Project that appear to show an Iron Order member with a gun — although an Iron Order attorney has branded both the shot and the statement "outright fabrications."

Here's a closer look at the photo above, without the inset gun image. According to 7News, Mendoza can also be seen in this shot; he's described as a bearded man wearing sunglasses at the bottom of the staircase.

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The photo was snapped by an NCC member who was present at the time — and the organization's attorney, Wade Eldridge, is also said to have seen what went down.

Thus far, no one has been arrested or charged in the killing. But the NCC release has plenty of negative things to say about the Iron Order. Here's an excerpt:

The Iron Order Motorcycle Club has been involved in a laundry list of confrontations around the country with other motorcycle clubs that have resulted in violence or death. For example, on June 26, 2014, Florida State Attorney Angela Corey refused to charge Iron Order prospect Kristopher Stone after he shot and killed Black Pistons patch holder Zachariah Tipton in Jacksonville Beach. Corey outrageously ruled the killing was justifiable homicide even though the Iron Order member shot the unarmed Black Pistons motorcycle club member in the face while only a few feet apart.

The release characterizes the Iron Order as "an off-duty law enforcement officer based motorcycle club" that "repeatedly diminishes the relationship between law enforcement and the community they are intended to serve and protect."

At this point, there's no confirmation about brawl participation by other law enforcement members beyond the Colorado Department of Corrections employee (who an Iron Order attorney says fired a weapon in self-defense).

But many members of the motorcycle community seem incensed about what happened.

Here's a Facebook post from a group called People Against Cop Killers that mentions the so-called 1 Percenters. The reference is to the 1 percent of motorcycle club members who are outlaws, as opposed to the 99 percent who are law-abiding citizens.

Being the Founder of P.A.C.K (People Against Cop Killers) and part of the Motorcycle Community and someone who helps with Promoting Motorcycle Events this SICKENS me .........I know alot of People in Clubsboth Police type and all others.............QUIT MEASURING YOUR DICKS..........All you have to have is one MORON on either side and Families are ruined.........And yes I know alot of Cop Groups to be just as big of A** HOLES as the 1% when they get in Public together...........You Ruin it for all of us.........I personally had the HORROR of seeing my own surronded by a Club.........but they Talked it out...LIKE MEN.......GROW UP.........Want to Fight .....use your FISTS, LIKE REAL MEN .